Direct burial refers to positioning bolts before pouring concrete, while post burial involves reserving bolt holes during concrete pouring. The advantages
of directly buried bolts are uniform concrete strength, strong integrity, and high shear strength; The disadvantage is that the bolt does not have a fixed
support point, and if there is a bolt positioning error, it can be very difficult to handle.
The advantage of buried foot bolts is that they have reliable support points, accurate positioning, and are not prone to errors; The disadvantage is that
the reserved holes in the concrete will harden and shrink after pouring, and it is easy to produce cracks between the original concrete, thereby reducing
the overall shear strength and affecting the overall durability of the structure. Nowadays, the commonly used method is the direct buried anchor bolt
method.
First, make a mold based on the position of the anchor bolts and determine the reference position. Usually, the center of mass of the column is used as
the positioning point, and the position of the bolt is based on the relationship between the center of mass of the column and the position of the bolt, as
well as the diameter of the bolt. The diameter of the drilled hole is 2mm larger than the diameter of the bolt, and the mold is 50mm larger than the outer
edge of the bolt group. Two identical molds can be made according to the thickness of the leveling layer to create a box of a certain thickness. This
way, the bolt will not shake left and right after being inserted into the mold, ensuring verticality. After inserting the bolt into the mold, tighten the nut t
the upper part to secure it, and then adjust the reserved height of the bolt. After fixing the basic short column template, please ensure that the template
is firm, and then align the reference point of the anchor bolt mold with the center of mass of the cylinder. Fix the mold onto the short column template
and securely connect it to the steel bars of the short column to prevent any movement of the steel bars.
Weld a short steel bar under the bolt in advance. To prevent the bolt from moving vertically, support the short steel bar on the concrete of the short
column foundation. After reinforcing the bolt, remove the mold to install the next set of anchor bolts. It is necessary to avoid displacement of the
anchor bolt due to concrete extrusion, and the concrete pump pipe should not be directly poured onto the anchor bolt. Use artificial cloth within 30cm
from the anchor bolts and the surrounding area. Do not vibrate excessively in the above areas when using a vibrating rod. Construction personnel need
to strengthen monitoring of the anchor bolts. Always use a spirit level and a theodolite to check each set of anchor bolts. If any deviation is found, it
should be corrected immediately.
